This application claims benefit of Japanese Patent Application No. 2000-371434 filed on Dec. 6, 2000, the contents of which are incorporated by the reference.
The present invention relates to arrayed waveguide grating, arrayed waveguide grating module, arrayed waveguide grating module waveguide compensation method, optical communication device and optical communication system and, more particularly, to the arrayed waveguide grating, which permits ready selection of wavelength to be used, the arrayed waveguide grating module using such arrayed waveguide grating, the arrayed waveguide grating module wavelength compensation method of compensating in the arrayed waveguide grating module and the optical communication unit and the optical communication system.
In optical fiber communication systems, further transfer capacity increase has been called for together with transmission data capacity increase. In DWDM (Dense Wavelength Division Multiplexing), the importance of the optical wavelength filter as multiplexing/demultiplexing device for multiplexing and demultiplexing wavelengths has been increasing.
Optical wavelength filters are of various types. Among the optical wavelength filters, the arrayed waveguide gratings have narrow wavelength characteristic and high extinguishing ratio, and they further have features as multiple-input multiple-output filter device. Thus, the optical wavelength filters capable of demultiplexing the multiplexed signals and performing inverse operation, and thus it can readily constitute a multiplexing/demultiplexing device. By using quarts waveguide for the arrayed waveguide grating, it is possible to obtain excellent coupling to optical fiber and realize low insertion loss operation with an insertion loss of several dB (decibels). The arrayed waveguide grating has attracting attention as particularly important device among the optical wavelength filters, and its extensive home and abroad researches and investigations are in force.
FIG. 18 shows the overall construction of a prior art arrayed waveguide grating. The arrayed waveguide grating 10 as shown comprises, formed on a substrate 11, one or more input waveguides 12, a plurality of output waveguides 13, a channel waveguide array 14 curved in a predetermined direction with different radii of curvature, an input side slab-waveguide 15 inter-connecting the input waveguides 12 and the channel waveguide array 14, and an output side slab-waveguide 16 inter-connecting the channel waveguide art 14 and the output waveguides 13. A multiplexed light signal inputted from the input waveguide or waveguides 12 to the input side slab-waveguide 15 is expanded as it passes therethrough and then inputted to the channel waveguide array 14.
The channel waveguide array 14 includes a plurality of arrayed waveguides with lengths progressively increasing or decreasing by a predetermined waveguide length difference. The light signals passing through the these arrayed waveguides reach the output side slab-waveguide 16 one after another by a predetermined phase difference internal. Actually, however, wavelength dispersion is present, and the in-phase plane is tilted independence on the wavelength. Consequently, the light signals are focused (i.e., converged) on different positions on the interface between the output side slab-waveguide 16 and the output waveguides 13. With the output waveguides 13 disposed at the positions corresponding to the respective wavelengths, it is possible to take out a desired wavelength component from the output waveguides 13.
In the meantime, in such arrayed waveguide grating 10, the wavelength selection should be performed in conformity to the grid of the ITU (International Telecommunication Union). The wavelength of the arrayed waveguide grating 10, by the way, is very susceptible to the refractive index changes of the waveguide material. This means that the center wavelength as selected wavelength is subject to variations due to fluctuations in a film formation process as manufacturing process. Therefore, it is frequently impossible to obtain a value as desired. Also, the selected wavelength variation poses a problem that the optical loss with the wavelength in use is increased. Accordingly, it has been in practice to do wavelength compensation to a proper value by some means after completion of the arrayed waveguide grating.
For example, according to Japanese Patent Laid-Open No. 9-49936 an input/output waveguides for wavelength compensation are provided in addition to the normal input/output waveguides based on AWG arrayed waveguide, and are changed according to the wavelength compensation amount.
Denoting the demultiplication direction angle difference with respect to the wavelength difference by xcex4xcex, in the arrayed waveguide grating it is possible to compensate for the center wavelength xcexin by an amount given by the following equation (1) by changing the positions of the output waveguides 12, i.e., the slab incidence angle xcex8in.
xcex4xcexin=(xcex4xcex/xcex4xcex8).xcex8inxe2x80x83xe2x80x83(1)
The input/output waveguides, however, are disposed discretely. Therefore, the wavelength compensation amount is also discrete, and it is possible to obtain wavelength compensation as desired. In order to obtain the wavelength compensation amount as desired, it is necessary to set the slab incidence angle xcex8in as desired.
According to Japanese Patent Laid-Open No. 2000-162453, the selected wavelength center is shifted by irradiating an AWG array part with infrared rays and thus changing the refractive index of the irradiated art. According to P. C. Clemens et al, IEEE Photon. Tech. Lett., Vol. 7, No. 10, pp. 1040-1041, 1955 and Transactions of Institute of Electronics and Data Communication Engineers of Japan, C-3-76, 2000, the selected wavelength compensation is performed by changing the position of light incidence on an input side slab-waveguide.
FIG. 19 shows the construction of an arrayed waveguide grating, which does selected wavelength compensation by changing the position of incidence of light on an input side slab-waveguide. In the proposal in the above P. C. Clemens et al, IEEE, Photon, Tech. LETT., Vol. 7, No. 10, pp. 1040-1041, 1995, the AWG wafer 21 of the substrate is severed at an input side slab-incidence part 22. The slab-incidence part 22 is reinforced with glass, and an input fiber 24 which is also reinforced with glass is bonded (i.e., secured by adhesive) to the slab-incidence part 22. At the time of the bonding, the centering is performed directly, and the position of the input fiber 24 is changed as desired in correspondence to the wavelength compensation amount.
FIG. 20 shows what is proposed in the Transactions of Institute of Electronics and Data Communication Engineers of Japan, C-3-76, 2000. This proposal is different from the above structure described in connection with FIG. 19, in which the input fiber 24 is bonded to the slab-incidence part 22. As shown in FIG. 20, an input fiber 31 is connected via a slab-introduction optical waveguide 32 to the input side slab-waveguide 33. The input and output side slab-waveguides 33 and 34 are formed on an AWG element wafer 35, and a channel waveguide array 36 is connected between these slab-waveguides. Output waveguides 38 are connected between the output side slab-waveguide 34 and a fiber array 37.
In addition to the above proposals, it is in practice to change the temperature of mainly the channel waveguide array part (see channel waveguide array 14 shown in FIG. 18) of the arrayed waveguide grating and change the wavelength by adjusting the refractive index width a thermo-optical effect thus obtained. To this end, a temperature controller such as a Velch element or a heater is used.
When carrying out such arrayed wavelength grating wavelength compensation as to match the ITU grid by the above various proposals or method, such high accuracy compensation with an error of several pm (picometers) is required. This demand is on an increasing trend together with the progress of the dense wavelength division multiplexing as noted above.
FIG. 21 shows an example of the spectrum shape of the light signal outputted from the arrayed waveguide grating. In the Figure, the ordinate is taken for the light signal output level of the arrayed waveguide grating, and the abscissa is taken from the wavelength. It is assumed that the same light signal output level has two different spectrum shapes 41 and 42. Of these spectrum shape, the relatively sharp spectrum shape 41 shown by dashed curve is capable of readily detecting the center wavelength. On the other hand, with the duller spectrum shape 42 it is difficult to detect the center wavelength. This means that in this case the accuracy of the center wavelength compensation is deteriorated.
FIG. 22 shows a different example of the spectrum shape of the light signal outputted from the arrayed waveguide grating. Of the two spectrum shapes 43 and 44 in this example, although their light signal output level integrals are equal, the spectrum shape 43 has a clear top, while the other spectrum shape 44 has a rather flat top. In order to reduce the loss variations in the ITU grid band as much as possible, a flat top shape such as the spectrum shape 44 is preferred. In this case, however, a problem is posed that the accuracy of the center wavelength compensation is deteriorated.
While problems in the arrayed waveguide grating have been discussed above, the same problems are also present in the arrayed waveguide grating module, optical communication device and optical communication system using such arrayed waveguide grating.
An object of the present invention, therefore, is to provide arrayed waveguide grating, arrayed waveguide grating module using such arrayed waveguide grating and arrayed waveguide grating module wavelength compensation method used for wavelength compensation in such arrayed waveguide grating module, which permit accurate center wavelength compensation of each waveguide in an arrayed waveguide grating, an arrayed waveguide grating module using such arrayed waveguide grating, an arrayed waveguide grating module waveguide compensation method use for wavelength compensation in such arrayed waveguide grating module, and optical communication device and optical communication system using such arrayed waveguide grating.
Various aspects and advantages thereof of the present invention which will be summarized as follows:
According to a first aspect of the present invention, there is provided an arrayed waveguide grating comprising: one or more input waveguides; an input side slab-waveguide connected to the output side of the input waveguide or waveguides; a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides; an output side slab-waveguide connected to the other terminal of the arrayed waveguides; a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides; and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides; the afore-said components being all formed on a substrate and the second output waveguide outputting an optical spectrum different from the optical spectral outputted from the other output waveguides.
In this embodiment, from the second output waveguide or waveguides among a plurality of output waveguide disposed on the output side of the arrayed waveguide grating, an output light signal spectrum different from the output light signal spectra from the other output waveguides are obtained, and they are used for center wavelength compensation of each waveguide of the arrayed waveguide grating.
According to a second aspect of the present invention, there is provided an arrayed waveguide grating comprising: one or more input waveguides; an input side slab-waveguide connected to the output side of the input waveguide or waveguides; a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides; an output side slab-waveguide connected to the other terminal of the arrayed waveguides; a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides; and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides; the afore-said components being all formed on a substrate and a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide.
In this embodiment, the connecting portion of the output waveguide disposed as second output waveguide among a plurality of output waveguides on the output side of the arrayed waveguide grating has a shape different from the shape of the connecting portion of the output waveguides as the output waveguides. By using these waveguides, the center wavelength compensation of each waveguide of the arrayed waveguide grating can be performed appropriately by changing the spectrum shape or like means.
According to a third aspect of the present invention, there is provided the arrayed waveguide grating according to one of the first and second aspects, wherein the second output waveguide constituting the output waveguides is a monitor light waveguide for wavelength monitoring.
In this embodiment, the second output waveguide is used as, for instance, a wavelength monitor.
According to a fourth aspect of the present invention, there is provided the arrayed waveguide grating according to the first aspect, wherein the second output waveguide constituting the output waveguides outputs an output spectrum having a narrower spectral width than the spectral width of the output optical spectra of the first output waveguides.
In this embodiment, the spectrum width of the spectrum of the light signal outputted from the second output waveguide is narrow compared to the usual waveguides as output waveguides. It is thus possible to readily specify the center wavelength, and the range in which errors occur is small.
According to a fifth aspect of the present invention, there is provided the arrayed waveguide grating according to the first aspect, wherein the second output waveguide constituting the output waveguides outputs an optical spectrum having a sharper peak than the peak of the optical spectra of the first output waveguides.
In this embodiment, the spectrum of the light signal outputted from the second output waveguide has a sharp peak compared to the usual waveguides as the output waveguides.
According to a sixth aspect of the present invention, there is provided the arrayed waveguide grating according to the second aspect, wherein the second output waveguide is a monitor light output waveguide and has a tapering connecting portion connected to the output side slab-waveguide.
In this embodiment, the terminal portion of the monitor light signal output waveguide connected to the output side slab-waveguide is tapering. Thus, the spectrum width is narrow, and a sharp spectrum is obtainable. However, the extent of tapering of the terminal portion is limited.
According to a seventh aspect of the present invention, there is provided the arrayed waveguide grating according to the second aspect, wherein the second output waveguide is a monitor light output waveguide and has a straight connecting portion with a fixed width direction dimension and connected to the output side slab-waveguide, and the first output waveguides constituting the output waveguides have terminal portions with progressively increasing width direction dimensions as one approaches the output side slab-waveguide.
In this embodiment, the monitor light signal output waveguide itself has a straight terminal portion connected to the output side slab-waveguide, while the first output waveguides each have a flaring terminal portion connected to the output side slab-waveguide. The terminal portion of the monitor light signal output waveguide connected to the output side slab-waveguide thus may not be necessarily tapering so long as it is made thin compared to the terminal portions of the first output waveguides.
According to an eighth aspect of the present invention, there is provided the arrayed waveguide grating according to the second aspect, wherein the waveguides constituting the output waveguides have terminal portions with progressively increasing width direction dimensions as one approaches the output side slab-waveguide, the terminal portions of the first output waveguides having width direction dimensions increasing at an increased rate.
In this embodiment, it is shown that the monitor light signal output waveguide constituting part of the output waveguides has the flaring connecting portion connected to the output side slab-waveguide. Again in this case, it is important in view of obtaining a satisfactory spectrum shape that the extent of flaring is less than the terminal portion of each first output waveguide.
According to a ninth aspect of the present invention, there is provided an arrayed waveguide grating module comprising: n arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the optical spectrum outputted from the second output waveguide being different from the optical spectra outputted from the other output waveguides; and optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating.
In this embodiment, this arrayed waveguide grating module is obtained by combining optical fibers and other components in the arrayed waveguide grating as set forth in connection with the first aspect of the present invention. The other component may be a temperature control circuit for controlling the temperature of the arrayed waveguide grating. This arrayed waveguide grating module also permits accurate center wavelength compensation of each output waveguide of the arrayed waveguide grating.
According to a tenth aspect of the present invention, there is provided an arrayed waveguide grating module comprising: an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the shape of the connecting portion of the second output waveguide with respect to the output side slab-waveguide being different from the shape of the connecting portion of the second output waveguides with respect to the output side slab-waveguide; and optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating.
In this embodiment, this arrayed waveguide grating module is obtained by combining optical fibers and other components in the arrayed waveguide grating as set forth in connection with the second aspect of the present invention. The other component may be a temperature control circuit for controlling the temperature of the arrayed waveguide grating. This arrayed waveguide grating module also permits accurate center wavelength compensation of each output waveguide of the arrayed waveguide grating.
According to an eleventh aspect of the present invention, there is provided a wavelength compensation method in an arrayed waveguide grating module comprising: a monitor light inputting step of inputting a monitor light for check from either one of the input waveguides with respect to an arrayed waveguide grating module with an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the optical spectrum outputted from the second output waveguide being different from the optical spectra outputted from the other output waveguides; and a wavelength compensation step of performing wavelength compensation with respect to the lights outputted from the first waveguides at the time of the light input from the input waveguides by detecting the monitor light outputted from the second output waveguide on the basis of the monitor light inputting step.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the first aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide.
According to a twelfth aspect of the present invention, there is provided a wavelength compensation method in an arrayed waveguide grating module comprising: a monitor light inputting step of inputting a monitor light for check from either one of the input waveguides with respect to an arrayed waveguide grating module with an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide; and a wavelength compensation step of performing wavelength compensation with respect to the lights outputted from the first waveguides at the time of the light input from the input waveguides by detecting the monitor light outputted from the second output waveguide on the basis of the monitor light inputting step.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the second aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide.
According to a thirteenth aspect of the present invention, there is provided a wavelength compensation method in an arrayed waveguide grating module comprising: a monitor light inputting step of inputting a monitor light for check from either one of the input waveguides with respect to an arrayed waveguide grating module with an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the second output waveguide outputting an optical spectrum different from the optical spectral outputted from the other output waveguides; an adjusting step of adjusting the arrayed waveguide grating module such that the second output waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting step; and a signal processing starting step of starting a signal processing by inputting actually used lights from the input waveguides of the arrayed waveguide grating module adjusted in the adjusting step and using wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the first aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide. Subsequently, a signal processing by inputting the actually used light signals from the adjusted arrayed waveguide grating module and using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating.
According to a fourteenth aspect of the present invention, there is provided a wavelength compensation method in an arrayed waveguide grating module comprising: a monitor light inputting step of inputting a monitor light for check from either one of the input waveguides with respect to an arrayed waveguide grating module with an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide; an adjusting step of adjusting the arrayed waveguide grating module such that the second output waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting step; and a signal processing starting step of starting a signal processing by inputting actually used lights from the input waveguides of the arrayed waveguide grating module adjusted in the adjusting step and using wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the second aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide. Subsequently, a signal processing by inputting the actually used light signals from the adjusted arrayed waveguide grating module and using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating.
According to a fifteenth aspect of the present invention, there is provided a wavelength compensation method in an arrayed waveguide grating module according to one of claims 3 and 4, wherein in the adjusting step the arrayed waveguide grating module is adjusted by controlling the temperature of the arrayed waveguide grating by using a temperature control circuit assembled in the arrayed waveguide grating module such that the second output waveguide outputs a monitor light having a predetermined wavelength.
In this embodiment, in the wavelength compensation method in the arrayed waveguide grating module as set forth in connection with the thirteenth and fourteenth aspects of the present invention, the temperature of the arrayed waveguide grating is adjusted when matching the wavelength by using the monitor light signal. The wavelength compensation may also be made with any other method.
According to a sixteenth aspect of the present invention, there is provided an optical communication system comprising: an arrayed waveguide grating module including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the optical spectrum outputted from the second output waveguide being different from the optical spectra outputted from the other output waveguides, optical fibers each having one terminal optically connected to at least part of the output side of each of a plurality of waveguides constituting the output waveguides of the arrayed waveguide grating, and a temperature control circuit for controlling at least temperature of the channel waveguide of the arrayed waveguide grating; a monitor light inputting means, to which a monitor light for check is inputted from either one of the input waveguides at the time of checking the arrayed waveguide grating module; an adjusting step of adjusting the arrayed waveguide grating module such that the second output waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting means; and a signal processing starting means of starting a signal processing by inputting actually used lights from the input waveguides of the arrayed waveguide grating module adjusted in the adjusting means and using wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, in this optical communication system, which uses an arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the first aspect of the present invention, at the time of checking the arrayed waveguide grating module, the arrayed waveguide grating module is adjusted by inputting a monitor light signal for checking form either one of the input waveguides such that the monitor light signal outputted from the second output waveguide has a predetermined wavelength. A signal processing using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating, is then started by inputting the actually used light signals from the input waveguides of the arrayed waveguide grating module.
According to a seventeenth aspect of the present invention, there is provided an optical communication system comprising: an arrayed waveguide grating module including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide, optical fibers each having one terminal optically connected to at least part of the output side of each of a plurality of waveguides constituting the output waveguides of the arrayed waveguide grating, and a temperature control circuit for controlling at least temperature of the channel waveguide of the arrayed waveguide grating; a monitor light inputting means, to which a monitor light for check is inputted from either one of the input waveguides at the time of checking the arrayed waveguide grating module; an adjusting step of adjusting the arrayed waveguide grating module such that the second output waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting means; and a signal processing starting means of starting a signal processing by inputting actually used lights from the input waveguides of the arrayed waveguide grating module adjusted in the adjusting means and using wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, in this optical communication system, which uses an arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the first aspect of the present invention, at the time of checking the arrayed waveguide grating module, the arrayed waveguide grating module is adjusted by inputting a monitor light signal for checking form either one of the input waveguides such that the monitor light signal outputted from the monitor light waveguide has a predetermined wavelength. A signal processing using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating, is then started by inputting the actually used light signals from the input waveguides of the arrayed waveguide grating module.
According to an eighteenth aspect of the present invention, there is provided an optical communication system comprising: an optical transmitting means for transmitting lights having individual wavelengths as parallel signals; a multiplexer constituted by an arrayed waveguide grating for multiplexing the optical signals with the individual wavelengths transmitted from the optical transmitting means; a light transmitting line, along which the multiplexed light outputted from the multiplexer is transmitted; a node having the array waveguide grating appropriately arranged in the light transmitting line; a demultiplexer for demultiplexing the light transmitted from the light transmitting line via the node in order to separate the lights of respective wavelengths; an optical receiving means for receiving the demultiplexed light with the individual wavelengths outputted from the demultiplexer; the demultiplexer being an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the light inputted to the second output waveguide having a spectrum shape different from the spectrum shape of the lights inputted to the first output waveguides.
In this embodiment, in the optical communication system comprising a light signal transmitting means for transmitting light signals of different signals, a multiplexer constituted by an arrayed waveguide grating for multiplexing the light signals of the individual wavelengths outputted form the light signal transmitting means, a light signal transmitting line for transmitting the multiplexed light signal outputted from the multiplexer, a node disposed on the light signal transmitting line on an appropriate position thereof and including an arrayed waveguide grating, a demultiplexer constituted by an arrayed waveguide grating for demultiplexing the inputted light signal transmitted along the light signal transmitting line and through the node to separate the light signals of the individual wavelengths, and a light signal receiving means for receiving the separated light signals of the individual wavelengths from the demultiplexer, the demultiplexer is constituted by the arrayed waveguide grating as set forth in connection with the first aspect of the present invention.
According to a nineteenth aspect of the present invention, there is provided an optical communication system comprising: an optical transmitting means for transmitting lights having individual wavelengths as parallel signals; a multiplexer constituted by an arrayed waveguide grating for multiplexing the optical signals with the individual wavelengths transmitted from the optical transmitting means; a light transmitting line, along which the multiplexed light outputted from the multiplexer is transmitted; a node having the array waveguide grating appropriately arranged in the light transmitting line; a demultiplexer for demultiplexing the light transmitted from the light transmitting line via the node in order to separate the lights of respective wavelengths; an optical receiving means for receiving the demultiplexed light with the individual wavelengths outputted from the demultiplexer; the demultiplexer being an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide.
In this embodiment, in the optical communication system comprising a light signal transmitting means for transmitting light signals of different signals, a multiplexer constituted by an arrayed waveguide grating for multiplexing the light signals of the individual wavelengths outputted form the light signal transmitting means, a light signal transmitting line for transmitting the multiplexed light signal outputted from the multiplexer, a node disposed on the light signal transmitting line on an appropriate position thereof and including an arrayed waveguide grating, a demultiplexer constituted by an arrayed waveguide grating for demultiplexing the inputted light signal transmitted along the light signal transmitting line and through the node to separate the light signals of the individual wavelengths, and a light signal receiving means for receiving the separated light signals of the individual wavelengths from the demultiplexer, the demultiplexer is constituted by the arrayed waveguide grating as set forth in connection with the second aspect of the present invention.
According to a twentieth aspect of the present invention, there is provided an optical communication system comprising: a first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected one after another in the form of a loop by respective transmission lines, the nodes each demultiplexing a multiplexed light to separate a light having a corresponding wavelength, and a second arrayed waveguide grating multiplexing the separated lights of the individual wavelengths; the first arrayed waveguide grating being an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the second output waveguide outputting an optical spectrum different from the optical spectral outputted from the other output waveguides.
In this embodiment, in the optical communication system, which comprises the first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected to one another in a loop fashion by respective transmission lines, a multiplexed light signal being transmitted to each of the transmission lines, the nodes each demultiplexing the multiplexed light signal to separate the light signals of the individual wavelengths, and a second arrayed waveguide grating for multiplexing the separated light signals of the individual wavelengths, the first arrayed waveguide grating is the arrayed waveguide grating as set forth in connection with the first aspect of the present invention. It is thus possible to obtain wavelength compensation using the second output waveguide.
According to a twenty-first aspect of the present invention, there is provided an optical communication system comprising: a first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected one after another in the form of a loop by respective transmission lines, the nodes each demultiplexing a multiplexed light signal to separate a light signal having a corresponding wavelength, and a second arrayed waveguide grating multiplexing the separated light signals of the individual wavelengths; the first arrayed waveguide grating being an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide.
In this embodiment, in the optical communication system, which comprises the first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected to one another in a loop fashion by respective transmission lines, a multiplexed light signal being transmitted to each of the transmission lines, the nodes each demultiplexing the multiplexed light signal to separate the light signals of the individual wavelengths, and a second arrayed waveguide grating for multiplexing the separated light signals of the individual wavelengths, the first arrayed waveguide grating is the arrayed waveguide grating as set forth in connection with the second aspect of the present invention. It is thus possible to obtain wavelength compensation using the second output waveguide.
According to a twenty-second aspect of the present invention, there is provided the optical communication system according to one of the eighteenth to twenty-first, wherein a wavelength meter for wavelength monitoring in presetting the wavelength of at least one monitor light inputted to the at least one input waveguide of the first arrayed waveguide grating to a predetermined value when the monitor is inputted, is connected to the second output waveguide.
In this embodiment, the exclusive wavelength meter for monitoring the monitor light signal is used.
According to a twenty-third aspect of the present invention, there is provided the optical communication system according to one of the eighteenth to twenty-first aspects, comprising: a wavelength meter for being connected to the second output waveguide when a monitor light is inputted to the at least one input waveguide of the first arrayed waveguide grating; an adjusting means for adjusting the arrayed waveguide grating module such that the monitor light measured in the wavelength meter has a predetermined wavelength; and a signal processing starting means for starting a signal processing by causing the input of the actually used lights from the input waveguides of the arrayed waveguide grating module adjusted by the adjusting means and using the wavelength compensated lights outputted from the output waveguides of the arrayed waveguide grating.
In this embodiment, the optical communication system comprises a wavelength meter necessary for wavelength compensation for an arrayed waveguide grating module, an adjusting means for adjusting the arrayed waveguide, grating module by using the wavelength meter, and a signal processing starting means for starting a signal processing using the wavelength compensated light signals.
According to a twenty-fourth aspect of the present invention, there is provided an optical communication system comprising: an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and the optical spectrum outputted from the second output waveguide being different from the optical spectra outputted from the other output waveguides, and optical fibers each having one terminal optically connected to at least part of each of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating; and a module compensating means including a Mach zender circuit, in which a free spectral range as a interval corresponding to one cycle period of loss wavelength characteristic is preset as a desired optical frequency range, and to which the monitor light outputted from the second output waveguide is inputted when the monitor light is inputted to the at least one input waveguide of the first waveguide grating array, a first and a second photo-diodes for receiving respective beams branched out from the output side of the Mach zender circuit, a computing means for taking the ratio between the sum of the output currents from the two photo-diodes and the output current from either one of the two diodes, a deviation detecting means for detecting a wavelength deviation from the computed ratio, an adjusting means for adjusting the arrayed waveguide grating module by using the detection output from the deviation detecting means such that the monitor lights have a predetermined wavelength, and a signal processing starting means for starting a signal processing by causing input of the actually used lights from the input waveguides of the arrayed waveguide grating module adjusted by the adjusting means and using the wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, the optical communication device is constituted by using the first and second photo-diodes in the arrayed waveguide grating module as set forth in connection with ninth aspect of the present invention and also using a module compensating means for wavelength compensation by using a so-called wavelength detection locker. The wavelength meter itself is expensive, and the present invention as set forth in connection with the twenty fourth aspect of the present invention permits cost reduction of the optical communication device itself or an optical communication system using the same optical communication device.
According to a twenty-fifth aspect of the present invention, there is provided an optical communication system comprising: an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a plurality of arrayed waveguides formed on the side of the input side slab-waveguide opposite the input waveguide or waveguides, an output side slab-waveguide connected to the other terminal of the arrayed waveguides, a plurality of first output waveguides connected to the output side slab-waveguide on the side thereof opposite the arrayed waveguides and at least one second output waveguide formed together with the first output waveguides on the side of the output side slab-waveguide opposite the arrayed waveguides, the afore-said components being all formed on a substrate and a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide, and optical fibers each having one terminal optically connected to at least part of each of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating; and a module compensating means including a Mach zender circuit, in which a free spectral range as a interval corresponding to one cycle period of loss wavelength characteristic is preset as a desired optical frequency range, and to which the monitor light outputted from the second output waveguide is inputted when the monitor light is inputted to the at least one input waveguide of the first waveguide grating array, a first and a second photo-diode for receiving respective beams branched out from the output side of the Mach zender circuit, a computing means for taking the ratio between the sum of the output currents from the two photo-diodes and the output current from either one of the two diodes, a deviation detecting means for detecting a wavelength deviation from the computed ratio, an adjusting means for adjusting the arrayed waveguide grating module by using the detection output from the deviation detecting means such that the monitor lights have a predetermined wavelength, and a signal processing starting means for starting a signal processing by causing input of the actually used light signals from the input waveguides of the arrayed waveguide grating module adjusted by the adjusting means and using the wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, the optical communication device is constituted by using the first and second photo-diodes in the arrayed waveguide grating module as set forth in connection with tenth aspect of the present invention and also using a module compensating means for wavelength compensation by using a so-called wavelength detection locker. The wavelength meter itself is expensive, and the present invention as set forth in connection with the twenty fifth aspect of the present invention permits cost reduction of the optical communication device itself or an optical communication system using the same optical communication device.
According to a twenty-sixth aspect of the present invention, there is provided an arrayed waveguide grating comprising: at least one input waveguides; an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides; a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide; an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array; and a plurality of waveguides as output waveguides each having one terminal connected to the output side of the output side slab-waveguide, the optical spectrum of the light outputted from a second waveguide as one of the output waveguides being different from the optical spectrum of the lights outputted from first waveguides as the remaining output waveguides.
In this embodiment, a light signal spectrum different from the light signal spectrum outputted from the first waveguides, among the output waveguides connected to the output side slab-waveguide provided in the output side of the arrayed waveguide grating, is obtained from the second waveguide, and it is used for center wavelength compensation of each waveguide of the arrayed waveguide grating.
According to a twenty-seventh aspect of the present invention, there is provided an arrayed waveguide grating comprising: at least one input waveguides; an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides; a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide; an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array; and a plurality of waveguides as output waveguides each having one terminal connected to the output side of the output side slab-waveguide, a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide.
In this embodiment, a light signal spectrum different from the light signal spectrum outputted from the first waveguides, among the output waveguides connected to the output side slab-waveguide provided in the output side of the arrayed waveguide grating, is obtained from the second waveguide, and it is used for center wavelength compensation of each waveguide of the arrayed waveguide grating.
According to a twenty-eighth aspect of the present invention, there is provided the arrayed waveguide grating according to one of the twenty-sixth to twenty-seventh aspects, wherein the second output waveguide constituting the output waveguides is a monitor light waveguide for wavelength monitoring.
In this embodiment, the second output waveguide is used for the wavelength monitoring.
According to a twenty-ninth aspect of the present invention, there is provided the arrayed waveguide grating according to the twenty-sixth aspect, wherein the second output waveguide constituting the output waveguides outputs an output spectrum having a narrower spectral width than the spectral width of the output optical spectra of the first output waveguides.
In this embodiment, the spectrum width of the spectrum of the light signal outputted from the second output waveguide is narrow compared to the usual waveguides as output waveguides. It is thus possible to readily specify the center wavelength, and the range in which errors occur is small.
According to a thirtieth aspect of the present invention, there is provided the arrayed waveguide grating according to the twenty-sixth aspect, wherein the second output waveguide constituting the output waveguides outputs an optical spectrum having a sharper peak than the peak of the optical spectra of the first output waveguides.
In this embodiment, the spectrum of the light signal outputted from the second output waveguide has a sharp peak compared to the usual waveguides as the output waveguides.
According to a thirty-first aspect of the present invention, there is provided the arrayed waveguide grating according to the twenty-seventh aspect, wherein the second output waveguide is a monitor light output waveguide and has a tapering connecting portion connected to the output side slab-waveguide.
In this embodiment, the terminal portion of the monitor light signal output waveguide connected to the output side slab-waveguide is tapering. Thus, the spectrum width is narrow, and a sharp spectrum is obtainable. However, the extent of tapering of the terminal portion is limited.
According to a thirty-second aspect of the present invention, there is provided the arrayed waveguide grating according to the twenty-seventh aspect, wherein the second output waveguide is a monitor light output waveguide and has a straight connecting portion with a fixed width direction dimension and connected to the output side slab-waveguide, and the first output waveguides constituting the output waveguides have terminal portions with progressively increasing width direction dimensions as one approaches the output side slab-waveguide.
In this embodiment, the monitor light signal output waveguide itself has a straight terminal portion connected to the output side slab-waveguide, while the first output waveguides each have a flaring terminal portion connected to the output side slab-waveguide. The terminal portion of the monitor light signal output waveguide connected to the output side slab-waveguide thus may not be necessarily tapering so long as it is made thin compared to the terminal portions of the first output waveguides.
According to a thirty-third aspect of the present invention, there is provided the arrayed waveguide grating according to the twenty-seventh aspect, wherein the waveguides constituting the output waveguides have terminal portions with progressively increasing width direction dimensions as one approaches the output side slab-waveguide, the terminal portions of the first output waveguides having width direction dimensions increasing at an increased rate.
In this embodiment, it is shown that the monitor light signal output waveguide constituting part of the output waveguides has the flaring connecting portion connected to the output side slab-waveguide. Again in this case, it is important in view of obtaining a satisfactory spectrum shape that the extent of flaring is less than the terminal portion of each first output waveguide.
According to a thirty-fourth aspect of the present invention, there is provided an arrayed waveguide grating module comprising: an arrayed waveguide grating including at least one input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, the optical spectrum of the light outputted from a second waveguide as one of the output waveguides being different from the optical spectrum of the lights outputted from first waveguides as the remaining output waveguides; and optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating.
In this embodiment, this arrayed waveguide grating module is obtained by combining optical fibers and other components in the arrayed waveguide grating as set forth in connection with the twenty-sixth aspect of the present invention. The other component may be a temperature control circuit for controlling the temperature of the arrayed waveguide grating. This arrayed waveguide grating module also permits accurate center wavelength compensation of each output waveguide of the arrayed waveguide grating.
According to a thirty-fifth aspect of the present invention, there is provided an arrayed waveguide grating module comprising: an arrayed waveguide grating including at least one input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal; connected to the output side of the output side slab-waveguide, a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide; and optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating.
In this embodiment, this arrayed waveguide grating module is obtained by combining optical fibers and other components in the arrayed waveguide grating as set forth in connection with the twenty-seventh aspect of the present invention. The other component may be a temperature control circuit for controlling the temperature of the arrayed waveguide grating. This arrayed waveguide grating module also permits accurate center wavelength compensation of each output waveguide of the arrayed waveguide grating.
According to a thirty-sixth aspect of the present invention, there is provided a wavelength compensation method in an arrayed grating module having an arrayed waveguide grating which includes one or more input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, the optical spectrum of the light from a second waveguide, i.e., a monitor light waveguide, as one of the output waveguides connected to the input side of the output side slab-waveguide being different from the optical spectrum of the lights from first waveguides as the remaining output waveguides, the wavelength compensation method comprising a monitor light inputting step of inputting a monitor light for checking from either one of the input waveguides; and a wavelength compensation step of performing wavelength compensation with respect to the lights outputted from the first waveguides at the time of the light input from the input waveguides by detecting the monitor light outputted from the monitor waveguide on the basis of the monitor light inputting step.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the twenty-sixth aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide.
According to a thirty-seventh aspect of the present invention, there is provided a wavelength compensation method in an arrayed grating module having an arrayed waveguide grating which includes one or more input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, a connecting portion of the second output waveguide, i.e., a monitor light waveguide, with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide; the wavelength compensation method comprising a monitor light inputting step of inputting a monitor light for checking from either one of the input waveguides; and a wavelength compensation step of performing wavelength compensation with respect to the lights outputted from the first waveguides at the time of the light input from the input waveguides by detecting the monitor light outputted from the monitor output waveguide on the basis of the monitor light inputting step.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the twenty-seventh aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide.
According to a thirty-eighth aspect of the present invention, there is provided a wavelength compensation method in an arrayed grating module having an arrayed waveguide grating which includes one or more input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, the optical spectrum of the light from a second waveguide, i.e., a monitor light waveguide, as one of the output waveguides connected to the input side of the output side slab-waveguide being different from the optical spectrum of the lights from first waveguides as the remaining output waveguides; the wavelength compensation method comprising: a monitor light inputting step of inputting a monitor light for checking from either one of the input waveguides; an adjusting step of adjusting the arrayed waveguide grating module such that the monitor light waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting step; and a wavelength compensation step of performing wavelength compensation with respect to the lights outputted from the first waveguides at the time of the light input from the input waveguides by detecting the monitor light outputted from the monitor output waveguide on the basis of the monitor light inputting step.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the twenty-sixth aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide. Subsequently, a signal processing by inputting the actually used light signals from the adjusted arrayed waveguide grating module and using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating.
According to a thirty-ninth aspect of the present invention, there is provided a wavelength compensation method in an arrayed grating module having an arrayed waveguide grating which includes one or more input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, a connecting portion of the second output waveguide, i.e., a monitor light waveguide, with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide; the wavelength compensation method comprising: a monitor light inputting step of inputting a monitor light for checking from either one of the input waveguides; an adjusting step of adjusting the arrayed waveguide grating module such that the monitor light waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting step; and a wavelength compensation step of performing wavelength compensation with respect to the lights outputted from the first waveguides at the time of the light input from the input waveguides by detecting the monitor light outputted from the monitor output waveguide on the basis of the monitor light inputting step.
In this embodiment, this wavelength compensation method uses the arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the twenty-seventh aspect of the present invention. The wavelength compensation is performed by inputting the monitor light signal for checking from either one of the input waveguides and detecting the monitor light signal outputted from the second output waveguide. Subsequently, a signal processing by inputting the actually used light signals from the adjusted arrayed waveguide grating module and using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating.
According to a fortieth aspect of the present invention, there is provided the wavelength compensation method in an arrayed waveguide grating module according to one of the thirteenth to thirty-ninth aspects, wherein in the adjusting step the arrayed waveguide grating module is adjusted by using a temperature control circuit assembled in the arrayed waveguide grating module such that the monitor light waveguide outputs a monitor light having a predetermined wavelength.
In this embodiment, in the wavelength compensation method in the arrayed waveguide grating module as set forth in connection with the thirty-eighth and thirty-ninth aspects of the present invention, the temperature of the arrayed waveguide grating is adjusted when matching the wavelength by using the monitor light signal. The wavelength compensation may also be made with any other method.
According to a forty-first aspect of the present invention, there is provided an optical communication system comprising: an arrayed waveguide grating module including at least one input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal; connected to the output side of the output side slab-waveguide, the optical spectrum of the light outputted from a second waveguide, i.e., a monitor light waveguide, as one of the output waveguides being different from the optical spectrum of the lights outputted from the remaining output waveguides, optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating, and a temperature control circuit for adjusting at least the temperature of the channel waveguide array of the arrayed waveguide grating; a monitor light inputting means for inputting a monitor light for checking from either one of the input waveguides at the time of the arrayed waveguide grating check; an adjusting means of adjusting the arrayed waveguide grating module such that the monitor waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting step; and a signal processing starting means of starting a signal processing by inputting actually used lights from the input waveguides of the arrayed waveguide grating module adjusted in the adjusting means and using wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, in this optical communication system, which uses an arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the twenty-sixth aspect of the present invention, at the time of checking the arrayed waveguide grating module, the arrayed waveguide grating module is adjusted by inputting a monitor light signal for checking form either one of the input waveguides such that the monitor light signal outputted from the second output waveguide has a predetermined wavelength. A signal processing using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating, is then started by inputting the actually used light signals from the input waveguides of the arrayed waveguide grating module.
According to a forty-second aspect of the present invention, there is provided an optical communication system comprising: an arrayed waveguide grating module including at least one input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, a connecting portion of the monitor waveguide as the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide, optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating, and a temperature control circuit for adjusting at least the temperature of the channel waveguide array of the arrayed waveguide grating; a monitor light inputting means for inputting a monitor light for checking from either one of the input waveguides at the time of the arrayed waveguide grating check; an adjusting means of adjusting the arrayed waveguide grating module such that the monitor waveguide outputs a monitor light having a predetermined wavelength when the monitor light is inputted in the monitor light inputting step; and a signal processing starting means of starting a signal processing by inputting actually used lights from the input waveguides of the arrayed waveguide grating module adjusted in the adjusting means and using wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, in this optical communication system, which uses an arrayed waveguide grating module having the arrayed waveguide grating as set forth in connection with the twenty-seventh aspect of the present invention, at the time of checking the arrayed waveguide grating module, the arrayed waveguide grating module is adjusted by inputting a monitor light signal for checking form either one of the input waveguides such that the monitor light signal outputted from the second output waveguide has a predetermined wavelength. A signal processing using the wavelength compensated light signals outputted from the first output waveguides of the arrayed waveguide grating, is then started by inputting the actually used light signals from the input waveguides of the arrayed waveguide grating module.
According to a forty-third aspect of the present invention, there is provided an optical communication system comprising: an optical transmitting means for transmitting light signals having individual wavelengths as parallel signals; a multiplexer constituted by an arrayed waveguide grating for multiplexing the optical signals with the individual wavelengths transmitted from the optical transmitting means; a light transmitting line, along which the multiplexed light outputted from the multiplexer is transmitted; a node having the array waveguide grating appropriately arranged in the light transmitting line; a demultiplexer for demultiplexing the light transmitted from the light transmitting line via the node in order to separate the lights of respective wavelengths; an optical receiving means for receiving the demultiplexed light signal with the individual wavelengths outputted from the demultiplexer; the demultiplexer being an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array, and a plurality of waveguides as output waveguides each having one terminal connected to the output side of the output side slab-waveguide, the optical spectrum of the light outputted from a second waveguide as one of the output waveguides being different from the optical spectrum of the lights outputted from first waveguides as the remaining output waveguides.
In this embodiment, in the optical communication system comprising a light signal transmitting means for transmitting light signals of different signals, a multiplexer constituted by an arrayed waveguide grating for multiplexing the light signals of the individual wavelengths outputted form the light signal transmitting means, a light signal transmitting line for transmitting the multiplexed light signal outputted from the multiplexer, a node disposed on the light signal transmitting line on an appropriate position thereof and including an arrayed waveguide grating, a demultiplexer constituted by an arrayed waveguide grating for demultiplexing the inputted light signal transmitted along the light signal transmitting line and through the node to separate the light signals of the individual wavelengths, and a light signal receiving means for receiving the separated light signals of the individual wavelengths from the demultiplexer, the demultiplexer is constituted by the arrayed waveguide grating as set forth in connection with the twenty-sixth aspect of the present invention.
According to a forty-fourth aspect of the present invention, there is provided an optical communication system comprising: an optical transmitting means for transmitting light signals having individual wavelengths as parallel signals; a multiplexer constituted by an arrayed waveguide grating for multiplexing the optical lights with the individual wavelengths transmitted from the optical transmitting means; a light transmitting line, along which the multiplexed light outputted from the multiplexer is transmitted; a node having the array waveguide grating appropriately arranged in the light transmitting line; a demultiplexer for demultiplexing the light transmitted from the light transmitting line via the node in order to separate the lights of respective wavelengths; an optical receiving means for receiving the demultiplexed light with the individual wavelengths outputted from the demultiplexer; the demultiplexer being an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array, and a plurality of waveguides as output waveguides each having one terminal connected to the output side of the output side slab-waveguide, a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide.
In this embodiment, in the optical communication system comprising a light signal transmitting means for transmitting light signals of different signals, a multiplexer constituted by an arrayed waveguide grating for multiplexing the light signals of the individual wavelengths outputted form the light signal transmitting means, a light signal transmitting line for transmitting the multiplexed light signal outputted from the multiplexer, a node disposed on the light signal transmitting line on an appropriate position thereof and including an arrayed waveguide grating, a demultiplexer constituted by an arrayed waveguide grating for demultiplexing the inputted light signal transmitted along the light signal transmitting line and through the node to separate the light signals of the individual wavelengths, and a light signal receiving means for receiving the separated light signals of the individual wavelengths from the demultiplexer, the demultiplexer is constituted by the arrayed waveguide grating as set forth in connection with the twenty-seventh aspect of the present invention.
According to a forty-fifth aspect of the present invention, there is provided an optical communication system comprising: a first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected one after another in the form of a loop by respective transmission lines, the nodes each demultiplexing a multiplexed light to separate a light having a corresponding wavelength, and a second arrayed waveguide grating multiplexing the separated lights of the individual wavelengths; the first arrayed waveguide grating being an element including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array, and a plurality of waveguides as output waveguides each having one terminal connected to the output side of the output side slab-waveguide, the optical spectrum of the light outputted from a second waveguide as one of the output waveguides being different from the optical spectrum of the lights outputted from first waveguides as the remaining output waveguides.
In this embodiment, in the optical communication system, which comprises a first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected to one another in a loop fashion by respective transmission lines, a multiplexed light signal being transmitted to these transmission lines, the nodes each demultiplexing the multiplexed light signal to separate the light signals of the individual wavelengths, and a second arrayed waveguide grating for multiplexing the separated light signals of the individual wavelengths, the first arrayed waveguide grating is the arrayed waveguide grating as set forth in connection with the twenty-sixth aspect of the present invention.
According to a forty-sixth aspect of the present invention, there is provided an optical communication system comprising: a first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected one after another in the form of a loop by respective transmission lines, the nodes each demultiplexing a multiplexed light signal to separate a light signal having a corresponding wavelength, and a second arrayed waveguide grating multiplexing the separated light signals of the individual wavelengths; he first arrayed waveguide grating being an element including one or more input waveguides, an input side slab-waveguide connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array, and a plurality of waveguides as output waveguides each having one terminal connected to the output side of the output side slab-waveguide, a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide.
In this embodiment, in the optical communication system, which comprises a first arrayed waveguide grating including a transmission line loop having a plurality of nodes connected to one another in a loop fashion by respective transmission lines, a multiplexed light signal being transmitted to these transmission lines, the nodes each demultiplexing the multiplexed light signal to separate the light signals of the individual wavelengths, and a second arrayed waveguide grating for multiplexing the separated light signals of the individual wavelengths, the first arrayed waveguide grating is the arrayed waveguide grating as set forth in connection with the twenty-seventh aspect of the present invention.
According to the forty-seventh aspect of the present invention, there is provided the optical communication system according to one of the forty-third to forty-sixth aspects, wherein a wavelength meter for wavelength monitoring in presetting the wavelength of at least one monitor light inputted to the at least one input waveguide of the first arrayed waveguide grating to a predetermined value when the monitor is inputted, is connected to the second output waveguide.
In this embodiment, the exclusive wavelength meter for monitoring the monitor light signal is used.
According to a forty-eighth aspect of the present invention, there is provided the optical communication system according to one of the forty-third to forty-sixth aspects, comprising: a wavelength meter for being connected to the second output waveguide when a monitor light is inputted to the at least one input waveguide of the first arrayed waveguide grating; an adjusting means for adjusting the arrayed waveguide grating module such that the monitor light measured in the wavelength meter has a predetermined wavelength; and a signal processing starting means for starting a signal processing by causing the input of the actually used light signals from the input waveguides of the arrayed waveguide grating module adjusted by the adjusting means and using the wavelength compensated lights outputted from the output waveguides of the arrayed waveguide grating.
In this embodiment, the optical communication system comprises a wavelength meter necessary for wavelength compensation for an arrayed waveguide grating module, an adjusting means for adjusting the arrayed waveguide grating module by using the wavelength meter, and a signal processing starting means for starting a signal processing using the wavelength compensated light signals.
According to a forty-ninth aspect of the present invention, there is provided an optical communication system comprising; an arrayed waveguide grating module including at least one input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, the optical spectrum of the light outputted from a second waveguide as one of the output waveguides being different from the optical spectrum of the lights outputted from first waveguides as the remaining output waveguides, and optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating; and a module compensating means including a Mach zender circuit, in which a free spectral range as a interval corresponding to one cycle period of loss wavelength characteristic is preset as a desired optical frequency range, and to which the monitor light outputted from the second output waveguide is inputted when the monitor light is inputted to the at least one input waveguide of the first waveguide grating array, a first and a second photo-diodes for receiving respective beams branched out from the output side of the Mach zender circuit, a computing means for taking the ratio between the sum of the output currents from the two photo-diodes and the output current from either one of the two diodes, a deviation detecting means for detecting a wavelength deviation from the computed ratio, an adjusting means for adjusting the arrayed waveguide grating module by using the detection output from the deviation detecting means such that the monitor lights have a predetermined wavelength, and a signal processing starting means for starting a signal processing by causing input of the actually used light signals from the input waveguides of the arrayed waveguide grating module adjusted by the adjusting means and using the wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, the optical communication device is constructed by using the first and second photo-diodes in the arrayed waveguide grating module as set forth in connection with the thirty fourth aspect of the present invention and adding the module compensating means for wavelength compensation using the so-called wavelength detecting locker. The wavelength meter itself is expensive, and the fiftieth aspect of the present invention permits cost reduction of the optical communication device itself or the entire optical communication system using the optical communication device.
According to a fiftieth aspect of the present invention, there is provided an optical communication system comprising: an arrayed waveguide grating module having an arrayed waveguide grating including one or more input waveguides, an input side slab-waveguide with the input side thereof connected to the output side of the input waveguide or waveguides, a channel waveguide array including a plurality of waveguides with lengths progressively increasing by a predetermined waveguide length difference, the input side of the waveguides being connected to the output side of the input side slab-waveguide, an output side slab-waveguide with the input side thereof connected to the output side of the plurality of waveguides constituting the channel waveguide array and a plurality of output waveguides each having one terminal connected to the output side of the output side slab-waveguide, a connecting portion of the second output waveguide with respect to the output side slab-waveguide having a shape different from the shape of connecting portions of the first output waveguides with respect to the output side slab-waveguide, and optical fibers each having one terminal optically connected to at least part of the plurality of waveguides constituting the output waveguides of the arrayed waveguide grating; a module compensating means including a Mach zender circuit, in which a free spectral range as a interval corresponding to one cycle period of loss wavelength characteristic is preset as a desired optical frequency range, and to which the monitor light outputted from the second output waveguide is inputted when the monitor light is inputted to the at least one input waveguide of the first waveguide grating array, a first and a second photo-diodes for receiving respective beams branched out from the output side of the Mach zender circuit, a computing means for taking the ratio between the sum of the output currents from the two photo-diodes and the output current from either one of the two diodes, a deviation detecting means for detecting a wavelength deviation from the computed ratio, an adjusting means for adjusting the arrayed waveguide grating module by using the detection output from the deviation detecting means such that the monitor lights have a predetermined wavelength, and a signal processing starting means for starting a signal processing by causing input of the actually used lights from the input waveguides of the arrayed waveguide grating module adjusted by the adjusting means and using the wavelength compensated lights outputted from the first output waveguides of the arrayed waveguide grating.
In this embodiment, the optical communication device is constructed by using the first and second photo-diodes in the arrayed waveguide grating module as set forth in connection with the thirty-fifth aspect of the present invention and adding the module compensating means for wavelength compensation using the so-called wavelength detecting locker. The wavelength meter itself is expensive, and the fiftieth aspect of the present invention permits cost reduction of the optical communication device itself or the entire optical communication system using the optical communication device.
Other objects and features will be clarified from the following description with reference to attached drawings.